Coking hydrocarbon oils



24, 1944- A. H. SCHUTTE 5 COKING-HYDROGARBON OILS Filed Ndv. 1S, 1941INVENTOR ATTO I Patented oer. 24, 1944 COKING HYDROCARBON OILS AugustHenry Schutte, Hastings on Hudson, N. Y., assignor to The LummusCompany, New York, N. Y., a corporation of Delaware Application November15, 1941, Serial No. 419,277

15 Claims.

This invention relates to an improved method of and an apparatus forcoking hydrocarbon material. More particularly, this invention isconcerned with the continuous production of coke from liquid orsemiliquid hydrocarbon or hydrocarbon-containing materials, especiallyheavy residual liquids resulting from the pyrolytic conversion ordistillation of hydrocarbon oils.

The manufactureof coke by the pyrolytic re: duction or distillation ofheavy petroleum residues and the like is well known. In the past,however, it has been customary to coke suchpetroleum residues in adiscontinuous manner requiring the use of a plurality of coking drums orchambers and resulting in cyclic operation because of the necessity ofperiodic removal of the coke formation from each chamber.

To overcome the disadvantages of this periodic operation, severalmethods of continuously coking petroleum residues have been proposed orsuggested. These methods, which usually provide for the formation ofcoke on a continuously moving surface or receptacle, have not beengenerally successful inasmuch as the resulting coke mass can not beconveniently, quickly, and entirely dislodged from the coking surfaceafter passage through the coking zone. Furthermore, difliculty isencountered in these methods in continuous removal of the dislodged andbroken coke mass from the coking apparatus, which may be maintainedunder a super atmospheric pressure.

It is an object of my invention to provide a continuous method forcoking hydrocarbon materials such-as petroleum residues, tars, and thelike whereby the disadvantages of prior continuous coking methods areavoided.

Another object of my invention is to provide a readily controlled methodof coking residual hydrocarbon material whereby such hydrocarbonmaterial is formed into a continuous layer which is passed through acoking zone for reduction to coke and subsequently subjected to adisrupting force for disintegration of the solidified coke mass.

It is a further object of my invention to provide an improved continuouscoking apparatus having means to form a continuously moving layer orfilm of hydrocarbon material to be coked, means to convert suchhydrocarbon material to coke, and means to dislodge and break up theresulting continuous coke mass by suitable disruption thereof.

Still another object of my invention is the provision of a method and anapparatus wherein the hydrocarbon material to be coked is formed into acontinuously moving layer having a con-- vex -lower surfaceand whereinthe resulting coke mass is disintegrated by distortion or. flexing ofthe convex lower surface of the coke layer.

It is also within the purview. of my invention to provide for thedischarge of the dislodged and broken coke mass from the coking zone.Accordingly, it is also an object of my invention to provide for usewith my continuous coking apparatus an improved liquid seal throughwhich the disintegrated coke mass is continuously discharged preferablywithout being wet by or undergoing reaction with the sealing liquidwhile the pressure within the apparatus is maintained at the desiredlevel.

Further. objects and advantages of my invention will be apparent fromthe following description thereof taken in connection with the at tacheddrawing, wherein:

Fig. 1 is a plan view, partly broken away and partly in section, of aform of apparatus for carrying out my improved method of continuouslycoking hydrocarbon material .in layer form.

Fig. 2 is a vertical cross section taken on line 22 of Fig. 1 showingthe liquid seal through which the dislodged coke mass is discharged fromthe coking apparatus.

Fig. 3 is a vertical cross section taken on line 3-3 of Fig. 1 showingthe arrangement of the flexible coking means and the heating meanstherefor.

Fig. 4 is a fragmentary vertical cross section taken on line 4-4 of Fig.1 showing the provision made for driving the flexible coking means.

In the preferred form of embodiment of my invention, the hydrocarbonmaterial to be coked is continuously deposited as a layer on an endlessbelt having a concave upper surface, which belt moves the hydrocarbonmaterial through a coking zone wherein it is subjected to temperaturessufiicient for conversion thereof to coke. The resulting coke layer isthen disintegrated and dislodged from the'belt by suitably flexing thebelt so that its upper surface is leveled or flattened as by passing thebelt over a cylindrical roller. The disrupted coke mass is dischargedfrom the coking apparatus by'passage through aseal comprising anonwetting, nonreactive liquid which simultaneously prevents the escapeof gases and vapors from the coking zone through the coke dischargeoutlet.

In the drawing, numeral i denotes an elongated vessel fabricated frommetal of suitable thickness to withstand the pressures and temperaturesrequired for converting hydrocarbon material to coke. This vesselpreferably is cytioned a pair of spaced, horizontal cylindrical rollers2 and 3, mounted respectively on shafts I and 5, which are in turnrespectively supported by side bearings 6 and I secured in the vesselwall. Rollers 2 and 3 preferably lie in the same horizontal plane, andthe shafts and bearings therefor are desirably constructed in such amanner as to prevent leakage of gases and vapors from vessel I.

According to my invention, a thin, endless, resilient, and flexible beltIII is carried by the spaced rollers and is positively driven as bymeans of the motor II connected to shaft 5 of roller 3. Belt IIIiscontinuous and nonsegmental for reasons more fully disclosedhereinafter. So that positive movement of the belt can be assured andthe possibility of slippage substantially eliminated, belt I0 isdesirably provided with a series of spaced openings I2 along each edgethereof for engagement with drive pins or sprockets I3 extendingradially from the peripheral edges of drive roller 3. Roller 2 may besimilarly constructed in order to assist in the continuous movement ofbelt III.

To accomplish the objects of my invention, I construct belt III of asuitable metal, desirably a heat-resistant alloy, that will maintain itscharacteristics of resiliency and flexibility upon continued subjectionto the relatively high temperatures required to effect the cokingoperation. The composition of this alloy is: desirably such that thebelt, when repeatedly deformed at the operating temperatures, continuesto resume its original shape. At the same time the metal of the'beltshould be able to withstand the normal corrosive action of thehydrocarbon material being treated. A suitable metal for this purposemay comprise a ferrous alloy containing molybdenum and/or nickel, forexample, or a nonferrous or substantially nonferrous alloy containingnickel such as Inconel (a product of The International Nickel 00., Inc.containing approximately80% nickel, 14% chromium, and 6% iron).

The belt is made thin enough so that, as it com tinuously passes betweenthe two rollers, it forms, because of its resiliency, a longitudinal,troughlike structure having a concave upper surface upon which theformation of the coke mass can take place. .At thesame time the thinstructure of the belt permits it to be flexed so that its concave uppersurface is substantially fiattened as it passes over each roller. Itwill be appreciated, of course, that the thickness of the belt and itstensile strength should be such that it can readily support the cokemass that forms thereon.

Vessel or chamber I is maintained at the desired coking temperature bymeans of hot gases flowing through longitudinal flue I5. These gases mayenter flue I5 through inlet passage I6 and may discharge therefromthrough exhaust passage I1. For this purpose, the hot combustion gasesfrom a cracking heater or the like may be used. Supplementary firing(not shown) to produce a separate suppb of hot flue gases may beprovided if such is necessary or if such is desired to control theheating within chamber I.

Flue I5 is preferably so constructed that its upper surface I8 isconcave and has the same general configuration as that assumed by theflexible belt III in its continuous movement between the rollers 2 and3. In this manner, belt lindrical in shape as shown but may haveanyother shape desired. Within this vessel is posi- III is supported bythe upper surface of flue II as it continuously moves thereover. Thecontact between belt I0 and the upper surface ofthe'fiue is made asclose and as complete as the speed with which belt III moves permits,and graphite may be used to facilitate the'movement of the belt. Thedirectionof movement of the belt is preferably countercurrent to that ofthe hot gases as shown, although both may move concurrently.

In operation, the hydrocarbon material tobe coked such as a heavyresidue, star, or the like is introduced into vessel I-tlirough line I 9and nozzle 20 and is continuously deposited on the moving belt III. Thecoking feed may comprise, for example, the heavy, tarry bottoms from thefuel oil flash tower of a combination cracking system, which feed may becharged directly to chamber I from such tower. The feedis preferablypreheated to some extent before being introduced into the coking vesseland is desirably at a temperature between 600 and 900 F. Where hot fueloil bottoms comprises the feed, its tem-' perature may be in theneighborhood of 750 F. When the temperature'of the feed is at thedesired coking temperature, the purpose of the hot gases in flue I5 isto supply primarily the endothermic heat necessary to effect coking ofthe residual hydrocarbons. When the temperature of the feed is below thedesired coking temperature, however, the hot flue gases also supply theheat necessary to raise the residual'hydrocarbon material to theoperating temperature. In the countercurrent operation shown, theresidual material to be coked is subjected to gradu ally increasingtemperatures, and progressive coking of such material thereby results.The rate of heating may also be so controlled that the resulting cokecan have substantially any desired degree of volatility.

The volatile hydrocarbons formed and vaporized from the residualmaterial during the coking operation are withdrawn from vessel I throughnozzle 2I and line 2Ia. These hydrocarbons may be condensed in condenser22, and the resulting condensate may be collected in accumulator 23,from which it may be withdrawn, if desired, by pump 24 for dischargethrough line 25. Preferably, these volatile hydrocarbons are subjectedto suitable conditions for further conversion thereof into gasoline andother desired products.

As the residual material is discharged onto belt I 0, it forms acontinuous layer or film, the lower surface of which becomes convex andassumes the configuration of the upper surface of the belt. The residualmaterial retains this layer form as it undergoes conversion into coke sothat a continuous layer of coke having a convex lower surface is movedtowards roller 3. Although the layer of residual material may be made asthick as desired, the desired volatility of the resulting coke and thecoking temperature employed are important factors to be considered inthe determination of the layer thickness in a particular operation.-

One of the salient features of the present invention is the provisionfor the disintegration of the solid coke layer formed on thecontinuously moving belt into fragments or lumps which are subsequentlydischarged from the coking vessel at the end opposite the residualmaterial inlet. According to my invention, this breaking up of the cokelayer is entirely automatic and is accomplished by flexing or exerting apressure on tinuously subjected to a disrupting force.

2,861,066 the belt as it reaches the drive roller 3 whereby the beltlsflattened and the-coke mass is con- As the belt is carried overtheroller, it is flexed or forced upwardly so that it becomessubstantially flat; and this action causes the cokelayer to break up anddisintegrate into fragments. I

At the same time, the belt passes around roller 3, and the disintegratedcoke mass iscontinuously dislodged'frombelt l0. During passage of thebelt over roller 3, there isa simultaneous radial and transverse actionwhich shears the layer of coke from the .beltat the plane of adherence.of the cokemass to the belt and causes the coke mass to crackandsubsequently to break into fragments. Substantially complete freeing orseparation of the coke layer from the moving belt is therebyaccomplished. It will be appreciated that conditions may be socontrolled as to obtain the coke in fragments of predetermined size. 1

The pieces of coke are discharged through opening 30 in vessel I-andpass through conduit 3| into the sealed conveyor 32, which dischargesthe broken coke from coking chamber I. In this discharge conveyor I makeprovision for maintaining a column of liquid through which the cokefragments must pass, which column-has a height suflicient to balance thedifferencein pressure, if any, between the coking chamber I and thedischarge side of conveyor 32. To accomplish this object, I prefer toconstruct conveyor 32 so that it has a substantially U-shaped configuration as shown and to provide a quantity of sealing liquid 33 in thelower portion of the U-tube.

and are discharged therefrom through conduit 42 fordisposal as'desired.If the coke fragments are to be stored, they may be subjected to aquenching operation after-discharge from con- .veyor32 and priorto'storage Discharge leg '40 is preferably, outwardly-and upwardlyflared as shown in order to prevent arching of the cokefragments withsubsequentnplugging of the-leg as the coke fragmentsrise through thesealing n um In order to maintain the'liquid seal at the desiredoperating temperature; I provide-a jacket 44 which surrounds vat-lea'stthe lower portion of the sealed conveyor 32. A suitable heating mediumsuch as a flue gasor the like may be circulated through this heatingjacket as by inlet 48 and outlet 41.

The liquid used to effect the seal should have certain characteristicsand should be selected with regard to the particular operatingconditions employed. It should have a freezing point sumciently belowand a boiling point sufilciently above the coking temperature so thatslight temperature variations Within the coking chamber will not alterits physical state. The specific gravity of the liquid should be suchthat the necessary liquid head to balance the differential pressure canbe maintained within a reasonable height. In addition, the specificgravity of the liquid should be greater than that of the coke so thatthe coke does not accumulate at the low point of the seal. The liquidshould have a high surface tension so that it does not wet or adhere tothe coke fragments in any way, and it should not react chemically withthe coke; otherwise, the discharge of the coke fragments through thesealed conveyor may not be satisfactorily accom plished. It is alsopreferable that gases dissolve in the sealing liquid to a negligibleextent.

In order to move the coke fragments through the resulting seal, Iprovide means to convey them from conduit 3| down through the seal-33.The conveying means may comprise any suitable conveying device, but Ifind that a continuous device such as an articulated link conveyor asshown at 35' is preferable. A motor 36 or the like is provided to drivethe continuous conveying device 35.

As the coke fragments are brought to the low point of the seal by theconveying device, they are freed therefrom and rise through the sealingliquid because of their much lower s ecific gravity. The well portion 38is preferably enlarged at 39 as shown to facilitate the freeing of thecoke fragments from the conveying device. The coke fragments risevertically through the liquid maintained in leg ill of the U-tubeconveyor 32 Molten metals are especially suitable as the sealing liquidsince the coking operation must be carried out at an elevatedtemperature. Because of their higher specific gravity, molten metalssuch as lead are particularly to be preferred when the coking operationmust be carried out at a. pressure in excess of atmospheric. Moltenalloys,

normally liquid metals such as mercury, or the like may also be used.

Molten lead is particularly satisfactory in that it has a specificgravity such that excessive heights of liquid are not required towithstand operating pressures below about pounds per square inch gage.Furthermore, it has a high surface tension so that it does not wet thecoke fragments, and it does not react chemically therewith. In addition,it does not materially vaporize at coking temperatures within the rangeof 700 to 1000 F,

It will be apparent that I have provided a process and an apparatuswherein residual hydrocarbon material to be coked is formed into a layeron a continuously moving carrying medium preferably having a concaveupper surface, from which the resulting coke mass is sheared at itsplaneof adherence to the carrying medium by flexing thereof, and whereinthe disintegrated coke mass is discharged from the coking zone withoutdisturbance of the continuous coking operating conditions.

It will be appreciated that certain features of my invention are notnecessarily limited to the coking of residual hydrocarbon materials. Forexample, my invention may also be applied to the coking of other typesof carbonaceous materials.

While I'have shown and described a preferred form of embodiment of myinvention, I am aware that modifications may be made thereto; and I,therefore, desire a broad interpretation of my invention within thescope and spirit of the description herein said of the claims appendedhereinafter.

What I claim is:

1. The method of continuously coking residual carbon material, whichincludes an elongated.

coking chamber, spaced rollers within said chamher, a continuouslymoving endless resilient metal belt carried by said rollers, the outersurface of said belt assuming a concave configuration between saidrollers. means to deposit hydrocarbon material to be coked in continuouslayer form on the concave outer surface of said endless belt. saidrollers flexing and flattening said belt as it passes thereover wherebythe resulting coke layerformed on the belt is disintegrated anddislodged, and a heating medium conduit positioned between said rollersto contact the convex under surface of .in fragments of coke arecontinuously discharged from the coking zone, the steps of sealing saidcoking zone against pressure leakage at the point of coke discharge,comprising maintaining at said point a volume of liquid nonwetting andnonreactive with respect to the coke, constraining said volume of liquidto form a column with a head suilicient to balance the differentialpressure between the coking zone and the external atmosphere,temperature-conditioning said liquid by circulation oftemperature-conditioned fluid therearound, and passing the fragments ofcoke through said column.

5. In a continuous coking process wherein the coking zone is maintainedunder predetermined pressure and temperature conditions and whereinfragments of coke are continuously discharged from the coking zone, thesteps of sealing said coking zone against pressure leakage at the pointof coke discharge, comprising maintaining at said point a volume ofmolten lead, constraining said volume of lead to form a column with ahead sufflcient to balance the pressure differential between the cokingzone and the external atmosphere, temperature-conditioning said volumeof lead by circulation of temperature-conditioned fluid therearound, andpassing the fragments of coke to the lower end of said column forflotation by the lead to the upper end of the column. 6. Apparatus forcontinuously coking hydrocarbon material, comprising means defining anelongated gas-tight coking chamber, a pair of rollers within and spacedalong said chamber and mounted for rotation on parallel horizontal axes,an endless resilient belt formed of a band of sheet metal trained aroundsaid rollers, means for driving one of said rollers to move the beltcontinuously. the outer surface of said belt assuming a concavecross-sectional configuration between said rollers, to form a shallowtrough of the upper run of the belt, means to continuously deposit fluidhydrocarbon material upon the belt at the trailing end of said trough toform a layer of the material within the trough, and means for supplyingheat to the said material upon the belt to coke the material as it istransported by the belt, the roller at the leading end of said troughbeing formed to flatten the belt as it passes thereover to therebydisintegrate the coke layer for subsequent dislodgment of the coke fromthe belt as the direction of the belt is changed by said roller.

7. Apparatus for continuously coking hydrocarbon material, comprisingmeans defining an elongated gas-tight coking chamber, a pair of rollerswithin said chamber and spaced therealong and mounted for rotation uponparallel horizontal axes, an endless resilient belt formed of a band ofsheet metal trained around said rollers, means for driving one of saidrollers to move the belt continuously, the outer surface of said beltassuming a concave cross-sectional configuration between the saidrollers to form a shallow trough of the upper run of the belt, means tocontinuously deposit fluid hydrocarbon material upon the belt at thetrailing end of said trough to form a layer of said material within thetrough, and a conduit for heating material extending along the underside of said run of the belt and having a transversely curved uppersurface conforming to the convex under surface of the belt and incontact therewith for supplying heat to said layer of material as it istransported by the belt, the one of said rollers at the leading end ofsaid beltrun being formed to flatten the belt asit passes thereover tothereby disintegrate the coke layer for subsequentdislodgment of thecoke from the belt as the direction of the belt is changed by saidroller.

8. In an apparatus for continuously coking residual hydrocarbon materialand including a coking chamber wherein coking is performed underpredetermined pressure and temperature conditions and wherein fragmentsof coke are continuously discharged through an outlet from said chamber,means for sealing said outlet against loss of pressure from saidchamber, comprising an approximately U-shaped conduit having one legthereof in gas-tight connection with said outlet to receive the cokefragments therefrom, a

volume of liquid in said conduit nonwetting and nonreactive with respectto the coke and heavier than coke, the other leg of said conduit havinga coke-discharging outlet, the volume of said liquid and said conduitoutlet being correlated to form of the liquid a column in said other legwith a head suflicient to balance the differential pressure between thecoking chamber and the external atmosphere, and a'conveyor within saidconduit for passing the coke from the receiving leg to the discharge legof the conduit for flotation in said liquid column to said conduitoutlet.

9. In an apparatus for continuously coking residual hydrocarbon materialand including a coking chamber wherein coking is performed underpredetermined pressure and temperature conditions and wherein fragmentsof coke are continuously discharged through an outlet from said chamber,

means for sealing said outlet against loss of pressure from saidchamber, comprising an approximately U-shaped conduithaving one legthereof in gas-tight connection with said outlet to receive the cokefragments therefrom, a volume of liquid in said conduit nonwetting andnonreactive with respect to the coke, the other leg of said conduithaving a coke-discharging outlet, the volume of said liquid and saidconduit outlet being correlated to form of the liquid a column in saidother leg with a head suflicient to balnace the differential pressurebetween the coking chamber and the external atmosphere, a conveyorwithin said conduit for passing the coke from the receiving leg to thedischarge leg of the conduit for fiotation in said liquid column to saidconduit outlet, and means for circulating temperatureconditioning fluidaround the exterior of said conduit for temperature-conditioning saidliquid.

10. The method of coking hydrocarbon material, comprising the steps ofdepositing said material upon a concave supporting surface to form alayer upon said surface, moving said layer, by advance of said surface,through a coking zone, maintaining said zone under conditions to convertthe material to coke and cause the coke to adhere to said surface,flexing said surface transversely of the direction of its advance todisintegrate the resulting coke layer, and flexing said surfacelongitudinally of said direction to dislodge the so-disintegrated cokefrom said surface.

11. The method of coking hydrocarbon material, comprising the steps ofdepositing said material upon a concave supporting surface to form alayer upon said surface, moving said layer, by advance of said surface,through a coking zone, conducting, within said zone, a constrainedstream of heating fluid beneath said surface and in indirect heatexchange relation to the latter to convert said material to coke andcause the coke to adhere to said surface, flexing said surfacetransversely of the direction of its advance to disintegrate theresulting coke layer, and flexing said surface longitudinally of saiddirection to dislodge the so-disintegrated coke from said surface.

12. The method of continuously coking hydrocarbon material, comprisingthe steps of continuously depositing said material from a fixed pointand upon a concave supporting surface to form a layer thereon,continuously moving said surface past said point to advance said layerthrough a coking zone, maintaining said zone under conditions to convertsaid material to coke, continuously flexing said moving surfacetransversely of its direction of movement at a point advanced from saidpoint of deposit to disintegrate the coke, and, at a point fartheradvanced from said fixed point, continuously flexing said surfacelongitudinally of its direction of movement to dislodge theso-disintegrated coke from said surface.

13. The method of continuously coking residual hydrocarbon material,comprisingthe steps of forming a continuous layer of said materialhaving a convex lower surface, continuously advancing said layer througha coking zone maintained under conditions to convert said material tocoke, and flexing the convex under surface of the resulting coke layertransversely of said movement of the coke layer to disintegrate thelatter.

14. In a continuous coking process wherein the coking zone is maintainedunder predetermined pressure and temperature conditions and whereinfragments of coke are continuously discharged from the coking zone, thesteps of sealing said coking zone against pressure leakage at the pointof coke discharge, comprising maintaining at said point a volume ofliquid, non-wetting and nonreactive with respect to the coke,constraining said volume of liquid to form a column with a headsuflicient to balance the differential pressure between the coking zoneand the external atmosphere, temperature-conditioning said liquid bycirculation of temperature-conditioned fluid in indirect heat exchangerelation to said liquid, and passing the fragments of coke through saidcolumn,

15. In a continuous coking process wherein the coking zone is maintainedunder predetermined high pressure and temperature conditions and whereinfragments of coke are continuously discharged from the coking zone, thesteps of sealing said zone against pressure leakage at the point of cokedischarge, comprising maintaining at said point a volume of moltenmaterial, nonwetting and non-reactive with respect to the coke andheavier than the coke, constraining said molten material to form acolumn with a head sufiicient to balance the pressure differentialbetween the coking zone and the external atmosphere, passing the cokefrom the coking zone to the base of said column free from the externalatmosphere, and then passing the coke upwardly through said' column byflotation.

AUGUST HENRY SCHUT'I'E.

